Abbreviation for radio frequency.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifth contact of the commutator up to a number determined by the design of the commutator. It then signals every contact except the fifth, which is ...

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

The actual time during which physical events take place.

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

A mercury barometer which measures atmospheric pressure by weighing the mercury in the column or cistern.

A c.g.s. (centimeter-gram-second) unit of mass. Originally defined as the mass of 1 cubic centimeter of water at 4

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

A hypothetical temperature characterized by a complete absence of heat and defined as 0 K, -273.15 C, or -459.67 F.

A unit measure of electrical conduction. The facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow. Electrical conductivity is the reciprocal of electric ...

An instrument which measures the scattering function of particles suspended in a medium in order to determine the visual range through the medium. See visibility meter.

The total amount of water transferred to the atmosphere by evapotranspiration.

A warm, dry wind on the lee side of a mountain range, the warmth and dryness due to adiabatic compression upon descent.

The maximum distance along the runway at which the runway lights are visible to a pilot at touchdown. Runway visual range may be determined by an observer located at the end of the runway, facing in the direction of landing, or by means of a transmissomet ...

The intensity (flux per unit solid angle) of visible radiation weighted to take into account the variable response of the human eye as a function of the wavelength of light. Usually expressed in candles.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

A clock-driven instrument mounting which automatically and continuously points in the direction of the sun. It is used with a pyrheliometera,hen continuous direct solar radiation measurements are required.

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.